Development of broadband hard x-ray radiography for pulsed power-driven warm dense plasmas

A solid material driven by Mega Ampere current from a pulsed power system is predicted to be in warm dense matter/plasma regimes. Such a high density, low temperature plasma can be created with a university-scale pulsed power generator by cylindrically compressing a thick metal wire. However, diagnosing the interior condition of the plasma in the enclosed geometry requires an external hard x-ray probe. To develop a short-pulse laser-based hard x-ray radiographic capability for pulsed power-driven high-density plasma, we carried out an experiment using a 50TW Leopard laser at the University of Nevada Reno's Zebra pulsed power laboratory. The intensity, spectrum and source size of broadband x rays produced by the laser interacting with silver targets (10, 20 and 100 μm thick foils and 25 μm diam. wire) were studied by measuring bremsstrahlung and radiographic images of solid Al wires. The measurements show that a high x-ray intensity was observed with the 10 μm thick foil, while a high contrast x-ray image was obtained with the wire. The results of the laser-only experiment, an optimized x-ray source target designed with a 3D hybrid particle-in-cell code, LSP, and the design of a laser-pulsed power coupled experiment will be presented.